Sheet-film cassette

ABSTRACT

A sheet-film cassette (1) comprises a lower portion (2) and a lid (3) hinged to said lower portion by means of a hinge (4). Hinge (4) consists of a flexible material and has a ledge-shaped profile with a thinner portion of the material forming a pivot zone (4e). Holding elements (4a, 4b and 4f, 4h respectively) which extend on either side of said pivot zone (4i) across the total length of the hinge are arranged for mounting the lower portion (2, 2f) and the lid (3, 3c) respectively. In order that a uniform pressure be exerted on the film, additional support means (4d, 4f) are molded to hinge (4), said support means being brought into positive engagement when cassette (1) is closed and stabilizing the total area of the hinge. For this purpose a ledge (4f) associated with the lower portion (2) is molded to hinge (4), which ledge extends across the whole length of the hinge into the interior of the cassette. When cassette (1) is in its closed condition, this ledge is positively engaged by a ledge (4d) associated with lid (3) and molded to hinge (4). 
     The ledges (4d) and (4f) as well as a projection (4j) extending into a recess (4k), which are also molded to hinge (4), extend over the total length of hinge (4) so that the hinge is sealed to prevent light from entering when cassette (1) is in its closed condition.

DESCRIPTION

The invention relates to a sheet-film cassette comprising a lowercassette portion serving to position the sheet film, an upper cassetteportion forming the cassette lid and including sheet-film pressuremeans, a narrow side wall connected to said lower portion, said uppercassette portion being held to said side wall, and thereby to said lowercassette portion, by a hinge, said hinge extending in a directionparallel to said side wall and having a surface aligned with the outersurface of said side wall, one part of the hinge being connected to theside wall, a second part of the hinge being connected to the uppercassette portion, the cassette also having a closing device which isarranged on the side of the cassette opposite to said hinge, the hingefurther comprising a first projection, which extends from the part ofthe hinge connected to the side wall in a direction parallel with thehinge and projects into the interior of the cassette, a secondprojection which extends from the part of the hinge connected to theupper cassette portion in a direction parallel with the first projectionand projects into the interior of the cassette.

In a cassette of this type which has been disclosed in DE-C1-34 01577the cassette lid is hinged to the lower cassette portion by a hingemade of flexible material and comprising a pivot zone formed by athinned section and having two claw-like holding elements to connect thecassette portions.

According to another cassette (PCT-A1-WO 82/00900) the cassette lid ishinged to the lower cassette portion by a plastic hinge, a flexiblepivot zone being formed by a thinned section of the material at thehinge. The hinge is fastened to a thin wall of the lower cassetteportion which in a manner known per se serves for positioning thecassette and for moving an X-ray film into close contact with a portionadapted to receive said film.

As a result of the thin wall of these cassettes and the thinned flexiblezone of their hinges, the stability of these cassettes in the area ofthe hinge is reduced so that uniform contact pressure of the film cannotbe guaranteed.

It is the object of the invention to provide a sheet-film cassette ofthe generic type such that in the area of the cassette hinge, too, auniform contact pressure by a cassette lid on the film is reached overthe whole length of the hinge.

In accordance with the invention this object is attained in that whenthe cassette is closed the second projection engages the firstprojection from below, whereby the projections support each other.

Avantageously, the hinge consists of a flexible material and has aledge-shaped profile with a pivot zone formed by a thinned section ofthe material. Holding elements extending in the longitudinal directionon either side of said pivot zone are provided for the cassette portionsas well as for the projections required for the support according to theinvention and for further elements provided for light-sealing purposes.

As a result of the design of the sheet-film cassette according to theinvention, the cassette, which is unstable in the area of the thin walland the pivot zone of the hinge when in its open position, is stabilizedwhen the cassette is closed. Thus the cassette lid and its pressuremeans respectively can exert uniform pressure on the film across thewhole length of the hinge.

Further features and advantages can be inferred from the description ofan embodiment of the invention illustrated in the drawings and from thesubclaims.

The drawings show schematically in

FIG. 1 a lateral view of a sheet-film cassette;

FIG. 2 a plan view of the cassette according to FIG. 1, and

FIG. 3 a sectional view along line A--A in FIG. 2, with only theessential areas illustrated and shown in section respectively.

The invention will be described with reference to an X-ray sheet-filmcassette which is preferably used for mamographic purposes and to thisend is designed with a relatively thin end wall so that the Xray filmcan be moved as closely as possible to the body.

The cassette 1 comprises a lower portion 2 to which a lid 3 is hinged bymeans of a hinge 4.

Lid 3 can be locked with a lower portion 2 of cassette 1 by means of aclosing device 7 of a type known per se and not illustrated in detail,which can be actuated either automatically or manually.

The lower portion 2 of cassette 1 has a support surface 2d for a sheetfilm 10, said support surface being surrounded by a circumferential wall2a, 2b of which wall portion 2b is thin and directly forms the outerwall of a narrow side of cassette 1.

Two spring elements 5, 6 are mounted to the lower portion 2 in aposition opposite to the thin wall 2b (FIG. 2) by hot rivets 11 with aslight pretention. As illustrated in FIG. 3, the free ends of the springelements 5, 6 extend into the closed receiving space for the sheet film10 and into recesses 2e of the support surface 2d.

Hinge 4 by which the lower portion 2 and the lid 3 are pivotablyconnected consists of a flexible material and, as shown in FIG. 3, has aledge-shaped profile with a thinned section which forms a pivot zone 4i.Holding elements extending over the whole length of the hinge are moldedon either side of said pivot zone 4i for mounting the lower portion 2and the lid 3 respectively. On the side of the lid, these holdingelements are formed by ledges 4a, 4b which enclose in a clawlike mannera T-shaped end section 3c of lid 3.

Ledges 4f and 4h molded to hinge 4 also enclose also in a clawlikemanner a beadlike portion 2f of thin wall 2b of lower portion 2.

As can be seen from FIG. 3, when the cassette 1 is closed, the area ofthe hinge is stabilized by a ledge 4d associated with lid 3, said ledgehaving an inclined surface 4e which positively engages below an inclinedsurface 4g of ledge 4f which is associated with the thin wall 2b.

The ledges 4d and 4f and a projection 4j extending into a recess 4k,which are also molded on hinge 4, extend over the total length of hinge4 so that the hinge is protected against the entrance of light whencassette 1 is closed. The end sides of hinge 4 are, moreover, covered bylateral projections 3a and 3b of lid 3 (see FIG. 2) as well as byintermediate labyrinth-type webs (not illustrated) on the lower portion2 and are thus sealed against the entrance of light.

Hinge 4 does not project beyond the plane of the outer surface 2c of thelower portion 2. Hinge 4 is fastened on the lower portion 2 and on lid 3by plugging and/or snapping.

At the inner side of lid 3, film pressure means of a type known per seare provided, said means comprising a foamed-plastic plate 8 and anintensifying screen 9 arranged thereon and extending directly up to theinner surface 2g of the thin wall 2b.

The foamed-plastic plate 8 is mounted on the inner side of lid 3, whichis not shown in detail, and is reinforced by ribs 3d arranged in a gridpattern.

Outside the range of the hinge, the lower portion 2 and the lid 3 ofcassette 1 are provided with walls interlocking in a knownlabyrinth-type configuration not illustrated to prevent light fromentering the cassette. When lid 3 is closed, one of those walls 3earranged on lid 3 (see FIG. 3) extends into the range of pivotalmovement of the spring elements 5 and 6 and displaces said elementslaterally.

When a sheet film 10 is loaded into the open cassette 1, the obliquelypositioned spring elements 5, 6 (shown in dash-dotted lines) direct thesheet film 10 into the receiving chamber of the cassette 1 such that itsfront edge is moved into direct contact with the inner surface 2g ofthin wall 2b.

When sheet film 10 is in its loaded position, its rear edge assumes aslightly elevated position as shown in dash-dotted lines in FIG. 3. Thisensures that the spring elements 5, 6 can always carry out their guidingfunction independently of the dimensional tolerances of the film.

The sheet film 10 having been loaded, lid 3 is closed. During suchoperation ledge 4d associated with lid 3 moves below ledge 4f associatedwith the thin wall 2b of lower portion 2 so that the inclined surfaces4e and 4g of said ledges are brought into positive engagement.

As a result, lid 3 is reliably supported and the whole area of the hingeis stabilized so that lid 3 exerts uniform pressure over the total widthof the cassette.

During closing of lid 3, the inclined surface 4g of ledge 4f acts on theinclined surface 4e of ledge 4d to press lid 3 together withfoamed-plastic plate 8 and intensifying screen 9 onto sheet film 10placed in lower portion 2, 2d. The relatively high initial pressureresults in the intimate contact required between intensifying screen 9and sheet film 10. The rolling effect between sheet film 10 and pressuremeans 8 and 9 initiated during closing of the lid 3--and subjecting thesurface to low pressure--is continued due to a slightly curved design ofthe inner side of lid 3 (not illustrated) and a slightly drum-shapeddesign of the support surface 2d in the lower portion 2 (not illustratedeither) until cassette 1 is closed. Thanks to the rolling effect duringclosing of cassette 1, air cannot be entrapped between sheet film 10 andits contact surfaces 2d and 9.

Shortly before lid 3 reaches its closing position, the spring elements5, 6, which are not used any longer, are pushed aside by the wall 3e ofthe lid so that the sheet film 10 can assume a perfectly plane positionalso in this area when cassette 1 is closed.

In contrast to the illustrated embodiment one of the longer sides of thehinge can also be molded directly to the lid or to the lower portion.Moreover, it is possible for the lower portion, the hinge and the lid toform an integral unit (not illustrated).

Another modification of the illustrated embodiment may consist in that(not illustrated) one or both support ledges 4d, 4f form part of lowerportion 2 and cassette lid 3 respectively, with the hinge 4 otherwisedesigned in the described manner or in another manner known per se.

The design of the hinge area according to the invention is advantageousnot only for a cassette as shown in the embodiment but also for acassette in which the hinge area must be stabilized in order to attainsmaller cassette dimensions.

I claim:
 1. Sheet-film cassette (1) comprising a lower cassette portion(2) serving to position the sheet film (10), an upper cassette portion(3) forming the cassette lid and including sheet-film pressure means(8), a narrow side wall (2b) connected to said lower portion (2), saidupper cassette portion (3) being held to said side wall (2b), andthereby to said lower cassette portion (2), by a hinge (4), said hinge(4) extending in a direction parallel to said side wall (2b) and havinga surface aligned with the outer surface (2c) of said side wall (2b),one part of the hinge being connected to the side wall, a second part ofthe hinge being connected to the upper cassette portion, the cassette(1) also having a closing device (7) which is arranged on the side ofthe cassette opposite to said hinge (4), the hinge (4) furthercomprising a first projection (4f), which extends from the part of thehinge (4) connected to the side wall (2b) in a direction parallel withthe hinge (4) and projects into the interior of the cassette, a secondprojection (4d) which extends from the part of the hinge (4) connectedto the upper cassette portion (3) in a direction parallel with the firstprojection (4f) and projects into the interior of the cassette,characterized in that when the cassette is closed the second projection(4d) engages the first projection (4f) from below, whereby theprojections (4d, 4f) support each other.
 2. Sheet-film cassetteaccording to claim 1, characterized in that the contact areas of thefirst and the second projection (4d, 4f) have inclined surfaces (4e, 4g)which allow the cassette lid (3) to carry out an unobstructed pivotalmovement.
 3. Sheet-film cassette according to claim 1 or 2,characterized in that the contact areas (4e, 4g) of the first and secondprojections (4d, 4f) engage in a light-sealing manner.
 4. Sheet-filmcassette according to claim 1, characterized in that the hinge (4),which consists of a flexible material, comprises a pivot zone (4i)formed by a thinned section of the material and claw-like holdingelements (4a, 4b; 4f, 4h) arranged on either side of said zone andassociated with the cassette portions (2, 3).
 5. Sheet-film cassetteaccording to claim 4, characterized in that the hinge (4) has aledge-shaped profile with holding elements (4a, 4b, 4f, 4h) extending inthe longitudinal direction, projections (4d, 4f, 4j), inclined surfaces(4e, 4g) and a recess (4k).
 6. Sheet-film cassette according to claim 4,characterized in that the claw-like holding elements (4f, 4h; 4a, 4b)engage correspondingly molded structures (2f; 3c) on the lower cassetteportion (2) and on the cassette lid (3) respectively.
 7. Sheet-filmcassette according to claim 4, characterized in that the firstprojection (4f) is arranged on the holding element (4f, 4h) of hinge(4), which is associated with the lower cassette portion (2), and thesecond projection (4d) is arranged on the holding element (4a, 4b),which is associated with the cassette lid (3).
 8. Sheet-film cassetteaccording to claim 4, characterized in that a third projection (4j) isarranged on the holding element (4f, 4h) associated with the lowercassette portion (2), which third projection covers the first projection(4f) and is arranged parallel therewith and extends further into theinterior of the cassette, and in that when cassette (1) is in its closedcondition, the third projection (4j) engages in a labyrinth-like fashionan associated recess (4k) in the holding element (4a, 4b) associatedwith cassette lid (3).